Piston



Oct. 9, 1945. R. M. DOUGLAS ET AL 2,386,668

PISTON Filed July 10, 1942 2 Sheets-Sheet l 7Z7 VACUUM I6 52 To AIRCLEANER Ivan/7553 HA W: 0 N0 M. DOA/61,48 RALPH JJ/w OK ATTORNEY 1945.R. M. DOUGLAS ET A1.

PISTON Filed July 10, 1942 2 Sheets-Sheet 2 .ZFWEN 70m Y ATTORNEYPatented Oct. 9, 1945 PISTON Raymond M. Douglas, Alpena, Mich., andRalph S. Huyck, South Bend, Ind., assignors to Bendix AviationCorporation, South Bend, Ind., a cor;

poration of Delaware Application July 10, 1942, Serial No. 450,376

11 Claims.

This invention relates in general to motors, and more particularly tothe piston or so-called power element of a pressure differentialoperated motor. When such a motor is energized the piston thereof issubjected to a differential of pressures resulting in a movement of thepiston to actuate the mechanism to which the piston is connected. It isof course desirable that the piston be of light weight and of relativelyfew parts. It is, however, particularly desirable that there beno-leakage of power fluid from one compartment of a double-ended motorto the other compartment or into or from the compartment of a singleacting motor. In other words, there should be a fluid-tight seal betweenthe inner wall of the cylinder of the motor and the periphery of thepiston. Accordingly, the principal object of our invention is to providea simple, durable and inexpensive piston construction effective toprevent the passage of air or other power fluid between the periphery ofthe piston and the cylinder wall and of such construction as to requirea minimum of service for a long period of time.

A further object of the invention is to provide a one-piece piston ofbut two materials, a synthetic compound and a metal, the metalconstituting the disk or body portion of the piston and the syntheticmaterial, which is bonded to the body portion, constituting theperipheral element of the piston.

Another object of our invention is to provide, in a motor having afollow-up valve therein, a piston requiring but a minimum of force tomove the same within the casing of, the motor, saidpiston beingconnected to one of the parts of the valve.

Other objects of the invention and desirable details of construction ofparts will become apparent from the following detailed description ofcertain embodiments of the invention, taken in conjunction with theaccompanying drawings i1- lustrating said embodiments, in which:

Figure 1 is a longitudinal sectional view of the servo-motor; Figures 2to 8 inclusive are sectional views of a detail of the piston structure,

Figures 1 to 6 inclusive and Figure 8 being modifications of thepreferred embodiment of our invention disclosed in Figure 7. Figure 9 isa perspective view of one of the elements of the servomotor.

Referring now to Figure 1 disclosing the piston constituting thepreferred embodiment of our invention, a double-acting, double-endedmotor in includes a casing I2, which houses a reciprocable piston H. Thecasing and piston together provide compartments I5 and I6 and it is thegaseous pressure within said compartments that effects the operation ofthe motor, The operation of the motor, that is the influx and efliux ofair or other power fluid into or from the compartments l5 and I6 iscontrolled by a so-called follow-up valve mechanism comprising aspool-shaped member liv mounted on the end of a hollow valve operatingrod i8 and the end portion 20 of a hollow connecting rod 22. The rod I8is preferably welded at 24 to a link 26 adjustably connected at 28 to amanually operated link 30 and the rod 22 is connected at 32 to a link 34connected to the mechanism to be actuated. The valve member 20 isprovided with ports 36 and 38 and the valve member I! is provided withdiagonally extending ducts 40 and 42. No claim is made to the valvemechanism disclosed inasmuch as said mechanism is described and claimedin United States Patent Number 2,212,955.

When the valve members are in the position disclosed in Figure 1 themotor is said to be deenergized, for at that time both compartments l5and 16 are vented to the atmosphere. Compartment i5 is vented via port36, a compartment 44 in the end of the rod 22, duct 40 in the valvemember H, the hollow connecting rod 22, a port 46 in the rod 22, a duct48 in a cylindrical end plate 50 and a nipple 52; -To the nipple 52there is connected an air cleaner not shown. The com partment i6 isvented to the atmosphere via port 38, the hollow connecting rod 22, port46, duct 48, nipple 52 and the air cleaner.

In order to energize the motor, that is efiect a movement-of its piston,the spool-shaped valve member I! is moved either to the right or left,Figure 1, said movement being effected by the manual operation of thelink 30. If the movement is to the right, one end of the member I! movesacross the port 38 thereby placing the duct 42 in fluid transmittingconnection with the compartment IS, the duct 42 opens into the hollowrod I8 to which is connected a conduit 54 le'ad ing to a source ofvacuum such as the intake manifold of an internal combustion engine;"ac-' cordingly, when the valve member I1 is moved tothe right thecompartment is is partially evacuated, the air from said compartmentflowing through the port 38, a recess 56 in the valve member l1, duct42, hollow rod I 8 and the conduit 54.

The piston i4 is then moved to the right, for it will be remembered thatthe compartment I5 is at the time vented to the atmosphere. The pistonis therefore subjected to a differential of pr'essures effecting thismovement. If movement of the manually operated valve member I] isstopped before the piston has completed its stroke, the piston willcontinue moving until the gaseous pressures within the compartments Itand II are such as to place the system in equilibrium. Describing thisoperation, valve member Il may follow up, that is move to a so-calledlapped position, that is when a full-bodied end portion ll of the valvemember I] is positioned over the port ll to prevent a flow of airthrough said port; or the resistance to movement of the piston may besuch as to. result in a follow-up movement of the valve member to againvent the compartment It to the atmosphere. The valve members l1 and 20would then again be in the position disclosed in Figure 1. I

Having described the operation of the motor to effect a movement'of thepiston 14 to the right it is not believed necessary to describe indetail the reverse operation of the motor to effect a movement of thepiston to the left, for functionally these operations are identical, aswill be apparent from an inspection of Figure 1, the latter operationbeing effected by moving the manually operated valve member I I to theleft to connect the compartment it with the source of vacuum.

There is thus provided a simple and compact double-acting motorcontrolled by a follow-up valve, said motor including one embodiment ofthe piston constituting our invention. The means or so-called workactuated by the pistons follows the movement of the manually operatedlink ll, said link being connected 1. e.,to a brake pedal, a clutchpedal or a selector mounted beneath the steering wheel for controllingthe transmission; for after the valve is opened by moving the link II.the piston and the mechanism connected thereto is moved and should themovement of the selector or brake pedal or clutch pedal be stoppedbefore its movement is completed then the movement of the mechanismbeing operative is also stopped. Should the motor, that is the powermeansxfail for any reason. then the mechanism to be operated will beactuated solely by physical effort; for in such an event a pin I'Isecured to the link It will contact one end or the otherofaslotilinthelinkil.

It is desirable to prevent relative movement of I the valve members I!and 20 which movement may be caused by jarring the motor II and theforce transmitting mechanism connected to the valve members. It isassumed, for example, that the motor is employed to operate or aid inthe der to prevent this operation of the valve there is housed withinthe motor a bent wire member ll, one end 82 of which partially encirclesthe rod It. It is bent upwardly at N and curved outwardly at l and I.The member 00 is frictionally held, in position on the rod II, thecircular shaped end .2 fitting tightly about said rod.

The curved sides I! and N of the member I. are slightly distorted whenthe rod II and head member I! are slid within the hollow rod 22;accordingly, the sides I and II which are under tension, provide a meanssetting up a frictional resistance to relative movement of the rods l1and 22. This resistance is of course overcome by "H of a metal disk-Gil.

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the driver of the car when, in opening the valve. he moves thetransmission controlling selector lover mounted adiacent the steeringwheel: and this resistance is also overcome when the piston is moving toeffect the above described follow-up action of the valve. Accordingly,the spring ll serves to prevent relative movement of the valve memberswhen the driver's hand is removed from the selector lever.

Describing now the essence of our invention there is provided in thepiston l4 disclosed in Figures 1 and 7 and in the pistons disclosed inFigures 2 to 6 inclusive and Figure 8 which may be substituted for thepiston H, a simple and inexpensive element which in large measurecontributes to the efficiency and effectiveness of the motor I0.Describing in detail the construction of the preferred embodiment of thepiston which is disclosed in Figure I, a peripheral ring member I2,preferably of synthetic rubber-like material, is bonded to a brassplated peripheral section The synthetic material which may be any one ofbuna rubber, neoprene, corprene, or perbuna, is bonded to the peripheryof the disk It, the copper crystals of the brass plating having anaffinity for the synthetic material. The rubber or rubber-like syntheticmaterial of which the member 12 is made is characterized by having arelatively high permanent set, thereby preventing a sticking of thematerial to the cylinder walls. This material is also so constituted asto be easily slid over the inner surface of the cylinder. However, thespring ll prevents an untimely opening of the valve despite a lowfrictional resistance to movement of the piston l4.

Describing further the peripheral member or seal 11 disclosed in Figure7 the same is substantially triangular shaped in cross section, two ofthe apexes of said member constituting outwardly extending flexible lipsII and II which provide an effective seal against the passage of air orother power fluid between the seal and the inner surface of the motorcasing it. It will be noted that the top of the member 12 is flat exceptfor an annular rounded projection or head II in the center of saidmember. It is also to be noted that when the motor is deenergized, thatis when both compartments I! and I are vented to the atmosphere, theparts of the piston is assume the positions disclosed in Figure 7. Theinner surface of the cylinder if, the aforementioned flat portion of thepiston and the lips II and II then outline a compartment ll. With such astructure when the compartment II is evacuated air will, by virtue ofthe shape of the lip ll, flow out of the compartment ll into compartmentll. By virtue of the shape of both the lip II and the body of the seal12 and by virtue of their flexibility said lip and that portion of thebody of the seal immediately connected thereto, will be so distorted asto force the lip against the inner wall of the motor casing l2 shown bydotted lines in Figure 7; for the compartment II is at the time atatmospheric pressure and the compartment II will be partially evacuatedthereby creating a differential of pressures to effect this result. Andit follow that should the compartment ll be evacuated the lip II will beforced against the inner wall of the motor casing. The head 13 which isslightly spaced from the inner wall of the casing I! when the motor isdeenergized but which moves into contact with said wall when the motoris energized, serves as a means to steady and g de the piston as itmoves through the cylinder.

aasaoee two body plate members 84 and 86. curved outwardly adjacenttheir peripheries, serve to clamp in position a peripheral ring member88 of one of the aforementioned synthetic materials. The

major portion of this member is substantially triangular in crosssection and a rectangularshaped annular portion 90 of the member isclamped between the peripheral edges of the body members 84 and 86. Theouter face of the ring member 88 is provided with an annular bead 92 andthe face is shaped to provide lips 84 and 98 which together with theinner wall of the cylinder I2 and body of the ring member, outline acompartment 98.

The piston constituting that embodiment of our invention disclosed inFigure 3 consists of a ring member I substantially triangular shaped incross section. The outer face of said ring member is preferably soshaped that together with the inner wall of the motor casing I2 there isprovided a compartment I02. As with the previously described embodimentsof my invention disclosed in Figures 2 and 7 the edges of the ringmember I00 constitute lips, indicated by the reference numerals I04 andI08, which function as sealing members to prevent the passage of airfrom one compartment of the motor to the other when the motor isenergized.

Referring now to Figure 4 there is disclosed in this embodiment of ourinvention a ring member I08 which is substantially triangular shaped incross section. The inner apex of said ring member is extended to providean annular member I I 0 rectangular in cross section through whichextends the brass plated periphery of a disk shaped body member II2 ofsuitable metal such as steel. The outer face of the ring member I08 isshaped to provide lips H4 and I I8 which, together with the innersurface of the motor casing I2 and the body of said member, provide acompartment H8.

The ring member I20 of the piston disclosed in Figure 5 is substantiallyT-shaped in cross section, the base I22 of said member, which ispreferably wider than oppositely extending lip members I24 and I28,being recessed to receive the brass plated periphery of a disk shapedmetal body member I28.

Those embodiments of our invention disclosed in Figures 6 and 8 includering members which are similar in cross section to the ring memberdisclosed in Figure 7, the major portion of the body member beingtriangular shaped in cross section. Referring to the embodiment of ourinvention disclosed in Figure 6 a body portion I80 is extended toprovide a base portion I82 which is recessed to receive the brass platedperiphery of a disk shaped body member I84. The outer face of the bodyportion I30 is recessed to provide, together with the inner surface ofthe motor casing, a compartment I88 and also provide relatively thin lipmembers I38 and I40. An annular bead member I42 extends from one face atthe center thereof. I

The embodiment of our invention disclosed in Figure 8 comprises a ringmember the body portion I44 of which is substantially triangular shapedin cross section. A projection I48 extending inwardly from the bodyortion I44 is recessed to receive the brass plated periphery of a diskshaped metal body member I48 and said body portion is recessed on itsouter face to provide, together with the inner surface of the motorcasing I2, a compartment I50. The upper edges or apexes of the bodyportion I44 provide lips I52 and I54.

There is thus provided in the seven ernb ments of our inventiondisclosed in the drawin s one-piece motor pistons simple in constructilight in weight and each is effective serving 5 .the power element ofthe motor. The construction of said pistons is such as to prevent theflow of air or other power fluid from one compartment of the motor tothe other when the latter is being energized. Each of the pistonsdisclosed in the drawings cooperates well with the remainder of themechanism of the motor disclosed in Figure 1, for by virtue of theirweight and construction but little force is necessary to move saidpistons and they provide an eifecti e seal to prevent leakage of airfrom one mo r compartment to the other when the motor is enersized.

This application constitutes a continuationin-part of our applicationSerial No. 347,5 8 filed July 26, 1940; The latter application h nowmatured into Patent No. 2,294,331 dated August 25, 1942.

Although this invention has been described 1 connection with certainspecific embodiments, the principles involved are susceptible ofnumerous other ap lications that will readily occur to persons skilledin the art. The invention is, therefore, to be limited only as indicatedby the scope of the appended claims.

We claim:

1. A piston adapted for use in a pressure differential operateddouble-acting motor consisting of a disk shaped metal plate serving as abody member, said member having its surface brass plated adjacent itsperiphery, and a pcripheral seal member of synthetic rubber chemicallybonded to the brass plated area of the body member.

2. A piston for use in a. fluid motor comprising a disk-like body memberof metal and a one piece peripheral seal member of synthetic rubberlikematerial chemically bonded to the periphery of said metal body member.

3. A piston adapted to be used in a pressure differential operatedmotor, said piston comprising a relatively thin metal body membercircular in outline and further comprising a multisided seal member ofsynthetic rubber chemically bonded to the periphery of said body member.

4. In a fluid pressure operated motor, a piston comprising a metal diskshaped body member and a sealing ring of synthetic rubber chemicallybonded to the periphery of the body memher, said ring beingsubstantially triangular in cross section thereby providing two lipmembers and having one of its sides so recessed as to provide, togetherwith the inner wall of the cylinder of the motor, an annular pocketsubstantially triangular in outline.

5. A piston comprising a metal disk shaped body member and a ring ofsynthetic rubber permanently secured to the periphery of said bodymember, the major portion of said ring being substantially triangularshaped in cross section and the remainder of said ring constituting aprojection, substantially rectangular in cross section,

4 asaaeee Q extending from one of the apexes of said trianriphery of thebody member.

7. In a double-acting double-ended pressure differential operated motora piston comprising a disk shaped body member of metal and a flexibleannulus of synthetic rubber chemically bonded to the periphery of saidmember, said annulus being substantially triangular shaped in crosssection, its outer face being so recessed as to provide two lip membersone or the other of which is bent, when the motor is energized, toprovide a seal and prevent a flow of air from one compartment of themotor to the other.

8. In a double-ended double-acting pressure differential actuated motor,a piston comprising a disk shaped body member of metal and a flexiblering of synthetic rubber bonded to the periphery of said member, saidring being substantially T- shaped in cross section, its outer facebeing so shaped as to provide, in combination with the inner surface ofth casing of the motor, a compartment which is substantially triangularshaped in cross section and an annular bead having a rounded outersurface extending outwardly from the center portion of said outersurface.

9. In a double-acting double-ended pressure differential actuated motor,a piston comprising a flexible ring of synthetic rubber substantiallytriangular shaped in cross section the outer face of said ring beingrecessed and the inner portion thereof being provided with an annularmember substantially rectangular shaped in cross section,

together with a body member of metal consisting of two disk shapedmembers each being cupped at its outer periphery to house and securetherebetween the aforementioned annular member.

10. As a new article of manufacture, a packing member and supporttherefor, which includes a circular flat relatively stiff single disc ofsheet stock, and a single packing ring of flexible rubberlike materialextending about the disc edge and permanently secured thereto, thedifference between outer and inner radii of said ring beingsubstantially less than the radius of the disc, whereby the radialoverlap of ring and disc is substantially less than the radial extensionof the disc as a whole, said ring being bounded at its opposite sides bygenerally arcuate faces and increasing in longitudinal thicknessprogressively outwardly toward the edge of the disc, the outer face ofthe ring being concave, with its maximum diameter at the opposite lipedges.

11. As a new article of manufacture, a packing member and supporttherefor, which includes a circular flat relatively stiff single disc ofsheet stock, and a single packing ring of flexible rubberlike materialextending about the disc edge and permanently secured thereto, theopposed faces of said disc and said packing ring includinginterpenetrating portions, the difference between outer and inner radiiof said ring being substantially less than the radius of the disc,whereby-the radial overlap of ring and disc is substantially less thanthe radial extension of the disc as a whole, said ring being bounded atits opposite sides by generally arcuate faces and increasing inlongitudinal thickness progressively outwardly toward the edge of thedisc, the outer face of the ring being concave, with its maximumdiameter at the opposite lip edges.

RAYMOND M. DOUGLAS. RALPH S. HUYCK.

